Employee Benefit Plans Projected Benefit Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 48,684
Fair value of plan assets at end of year	$ 54,061	$ 48,684
Other Postretirement Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of Increase threshold using citigroup average life discount rate table	0.25%
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ 1,926	2,875
Interest cost	68	85	$ 206
Change in assumptions	26	(20)
Experience gain	104	732
Projected benefit obligation at end of year	1,700	1,926	2,875
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	3	15
Fair value of plan assets at end of year	0	3	15
Employer contributions	213	270
Defined Benefit Plan, Benefit Obligation, Benefits Paid	216	282
Pension Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	85,363	84,736
Service cost (1)	0	688	579
Interest cost	3,320	3,520	3,405
Change in assumptions	5,008	1,635
Experience gain	(458)	(44)
Projected benefit obligation at end of year	89,482	85,363	84,736
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	48,684	46,971
Actual return on plan assets	5,312	1,716
Fair value of plan assets at end of year	54,061	48,684	$ 46,971
Employer contributions	3,816	5,200
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ 3,751	$ 5,172